public class Test {
    public static void main(String []args) {
        Watched girl = new ConcreteWatched();
        Watcher watcher1 = new ConcreteWatcher();
        Watcher watcher2 = new ConcreteWatcher();
        Watcher watcher3 = new ConcreteWatcher();
        girl.addWatcher(watcher1);
        girl.addWatcher(watcher2);
        girl.addWatcher(watcher3);
        girl.notifyWatchers("ok");
    }
}
